This invention relates to air/oil separators used in closed loop oil seal systems for liquid ring vacuum pumps, and specifically an air/oil separator which incorporates a compact multi-chambered design for facilitating multiple stages of oil particulate separation.
The breadth of applications for liquid ring vacuum pumps has rapidly increased with the development of the multiple stage air/oil separators by Dekker Vacuum Technologies, Inc. of Michigan City Ind. The Dekker air/oil separator, which is the subject of U.S. Pat. No. 6,033,462 and is incorporated herein by reference, uses a multi-chamber, multi-stage design in addition to a conventional filter element, which creates multiple stages of oil particulate separation. In addition to using gravitational force and the coalescing of oil particulate within the filter element, the separator of this invention improves oil condensation within the accumulator using the aerodynamic or thermodynamic conditions created by the multi-chambered design of the accumulator. The multi-chambered design of the accumulator enables a greater portion of the oil particulate to be condensed from the oil mist before passing through the filter element. The multi-chambered design restricts and slows the flow of oil mist through the inner and outer reservoir chambers, creates a difference in ambient temperatures between the inner and outer reservoir chambers and alters the direction of flow of the oil mist through the separator.
The application of liquid ring vacuum pumps is still limited by the physical size and space requirement of a closed loop oil recirculation system. In order for liquid ring vacuum pump systems to be used in a wider range of application, particularly low pressure or low horsepower applications, the air/oil separators needed for the oil recirculation systems must be more compact and efficient. Small compact conventional air/oil separators are commercially available, but rely heavily on filter elements to separate the oil particulate from the oil smoke. Although multi-chamber, multi-stage air/oil separators have increased the functionality of closed loop liquid ring vacuum pumps, the physical size of the multi-chambered reservoir tanks or accumulators have limited their application to large industrial vacuum pump applications. Consequently, a compact multi-chamber, multi-stage separator design, which can be incorporated into a variety of applications where physical space is limited is desirable.
The air/oil separator of this invention has a compact multi-chambered design that allows the separator and vacuum pump to be used in applications where physical space is limited. The separator includes a rectangular reservoir tank and a tubular internal filter housing, which supports a filter element inside the reservoir tank. The filter housing extends horizontally inside the reservoir tank with an open distal end disposed within the reservoir tank and a closed proximal end protrudes from the proximal end wall of the reservoir tank. Extending horizontally across substantially the length of the reservoir tank, the filter housing and two internal baffle plates divide the reservoir tank into an upper inlet chamber and two collection chambers. An upper inlet chamber is defined by the upper surface of the filter housing and a middle baffle plate. The middle baffle plate extends vertically downward from the top wall of the reservoir tank below the bottom surface of the filter housing. The end baffle plate extends vertically upward from the bottom of the reservoir tank, and divides the collection chambers into primary and secondary collection chambers at the proximal and distal ends of the reservoir tank respectively. The outer diameter of the filter housing is less than the internal width of the reservoir tank. Consequently, a narrow passage is created between the tubular body of the filter housing and the side walls of the reservoir tank. This narrow passage allows the oil discharge to flow from the inlet chamber into the primary collection chamber and allows oil smoke to vent from the primary to the secondary collection chamber. The lower portions of the end baffle plate and the splash plate are perforated to allow liquid oil to flow along the bottom of the reservoir tank between the primary and secondary collection chambers.
Oil discharge from the vacuum pump is deposited into the inlet chamber through an inlet port in the upper wall of the reservoir tank. The oil discharge flows through the narrow passages between the end wall of the reservoir tank and filter housing into the primary collection chamber. Oil discharge flowing around the filter housing and running down the side walls of the reservoir tank falls onto a splash plate before settling at the bottom of the reservoir tank. The liquid oil collected in the bottom of the reservoir tank is used to resupply the vacuum pump and is drawn out through an outlet port. Oil smoke flows from the primary collection chamber over the end baffle plate into the second collection chamber by the continuous flow of oil discharge into the separator and the vacuum draw from the exhaust port in the filter housing. Oil smoke is vented from the primary collection chamber into the secondary collection chamber back through the narrow passage created by the filter housing only between the middle and end baffle plates. Once vented into the second collection chamber, the oil smoke flows through the filter element, which removes any remaining oil particulate.
The introduction of the filter housing within the reservoir directly below the inlet port provides several functional advantages. Using an internal filter housing allows a physically more compact separator design, but also provides efficient gains. The internal filter housing is used to divide the reservoir tank into multiple chambers and to restrict the flow of oil discharge and oil smoke within the reservoir tank. The position of the filter housing and splash guard prevents the flow of oil from falling directly into a pool of liquid oil collected at the bottom of the reservoir. The splash of oil into the oil pool is another source of oil smoke. The position of the filter housing and splash guard reduce oil splash by reducing the distance that oil falls as well as slowing and deflecting the flow of oil discharge into the reservoir. The position of the filter housing inside the reservoir tank also provides a thermodynamic advantage. The surface of the filter housing is cooled by the operation of the air flowing through the filter element. Consequently, the heated oil discharge from the vacuum pump is deposited on a surface of the filter housing, where it is cooled to a lower ambient temperature by the operation of the filter element. The cool curved surface of the filter housing immediately promotes the condensation of the oil discharge.
Accordingly, an advantage of this invention is that the air/oil separator uses a compact multi-chamber, multi-stage design, which facilitates efficient oil separation and collection inside a small physical package.
Another advantage of this invention is that the separator includes a rectangular reservoir tank and a tubular internal filter housing, which supports a filter element inside the reservoir tank to reduce the physical size of the separator.
Another advantage of this invention is that the introduction of the internal filter housing within the reservoir tank improves oil particulate separation.
Another advantage of this invention is that the internal filter housing is used to divide the reservoir tank into multiple chambers and to restrict the flow of oil discharge and oil smoke within the reservoir tank.
Another advantage of this invention is that the separator uses the internal filter housing and splash guards to reduce oil splash within the reservoir tank, which decreases oil smoke.
Another advantage of this invention is that operation of the filter element inside the internal filter housing cools the surface of the filter housing, which promotes condensation of the oil particulate.
Other advantages will become apparent upon a reading of the following description.